An overview of approximate models for the drying kinetics is given, including lumped diffusion models, retreating front models and the characteristic drying curve model. To keep this overview orderly, only drying bodies with a slab geometry and a constant temperature are considered. The presented models enable-in a relatively simple way-the characterization and description of the drying behavior. All model parameters are derived from drying curves of slabs. The methods given relate to porous and non-porous materials. An attempt is being made to give a consistent presentation of these methods coming from different literature sources, by using the same definitions, nomenclature and symbols for the model parameters involved. For a correct analysis of the practical usefulness of the given methods more experimental data are needed. Some additional conclusions and recommendations an given.